All the contents disclosed in Japanese Patent Application No. Hei11-159038 (filed on Jun. 7, 1999) and Hei11-340244 (filed on Nov. 30, 1999), including specifications, claims, drawings and abstract, are integrated with the present application by cross-reference to all these disclosed contents.
1. Field of the Invention
This invention relates to a data transceiving system, and particularly to the pre-reading control of module data transmitted in a carousel sending scheme.
2. Description of the Related Art
Data transmission services are now known which use satellites. These are services wherein, at a broadcast station, module data are repeatedly transmitted in a carousel sending scheme, and, at the receiver end, only necessary module data are received and displayed.
In such a transceiver system, data are repeatedly transmitted in a carousel sending scheme, wherefore it is possible to pre-read the transmitted data beforehand into the cache area of a memory in the receiver. By such pre-reading, it becomes possible to display data from hyperlinked files merely by reading them out from the cache area, making high-speed display possible.
There are limits, however, to the memory capacity used for the cache area in the receiver. And, conversely, with the carousel sending scheme, there are cases where a file is transmitted while being updated. That being so, there are cases where unlimited pre-reading becomes meaningless.
An object of the present invention is resolve the problems described in the foregoing, providing a data receiver that has only limited memory area, wherewith acquisition of necessary data is possible in a shorter time.
A data receiver that, out of module data transmitted in a carousel sending scheme with module identifiers attached, selectively receives module data to which prescribed module identifiers are attached, comprises:
module data selection means for selecting module data matching given selection conditions, and outputting those module data;
memory means capable of storing said data so output;
pre-read control means for sending selection conditions for pre-reading module data associated with module data output by said module data selection means to said module data selection means; and
empty capacity acquisition means for acquiring empty capacity in said memory means; wherein:
said pre-read control means decide whether or not volume of data in said module data subject to pre-reading is smaller than said empty capacity acquired and, when said volume of data in said module data is smaller, send selection conditions to said module data selection means so that those module data subject to pre-reading are selected.
A data receiver that, out of module data transmitted in a carousel sending scheme with module identifiers attached, selectively receives module data to which prescribed module identifiers are attached, comprises:
module data selection means for selecting module data matching given selection conditions, and outputting those module data;
memory means capable of storing said data so output; and
pre-read control means for sending selection conditions for pre-reading module data associated with module data output by said module data selection means to said module data selection means;
said data receiver further comprising:
empty capacity acquisition means for acquiring empty capacity in said memory means; and
total data volume acquisition means for acquiring total data volume of module data belonging to a group; wherein:
said pre-read control means decide whether or not total data volume in a group to which said module data subject to pre-reading belong is smaller than said acquired empty capacity and, when said total data volume is smaller, send selection conditions to said module data selection means so that all module data belonging to that group are selected.
A data receiver that, out of module data transmitted in a carousel sending scheme with module identifiers attached, selectively receives module data to which prescribed module identifiers are attached, comprises:
module data selection means for selecting module data matching given selection conditions, and outputting those module data;
memory means for storing said data so output;
data read means for searching said memory means and reading out needed data when a data read command is sent thereto;
pre-read control means for sending selection conditions to said module data selection means for pre-reading module data associated with data output to said memory means by said module data selection means; and
empty capacity securing means for securing empty area in said memory means larger than said data volume, so that module data subject to pre-reading sent from said module data selection means will be pre-read beforehand in said memory means.
While the novel features of the invention are set forth in a general fashion, both as to organization and content. Other objects and features of the present invention will be more apparent to those skilled in the art on consideration of the accompanying drawings and following specification wherein are disclosed several exemplary embodiments of the invention with the understanding that such variations, modifications and elimination of parts may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.